Gas blast circuit breaker for high alternating voltages

ABSTRACT

A high voltage gas blast circuit breaker is provided with series-connected pairs of contacts, one used to interrupt the circuit being protected, and the other used to close or make the circuit being protected. The contact used for circuit interruption may be operated synchronously to interrupt at or before a current zero. The contact used for closing the circuit may be operated when the instantaneous voltage across the contact is zero, thereby to prevent line voltage surges during closing. The operating circuits for the contacts are at the high voltage side of the breaker and contain a generator driven from ground by an insulation shaft. The operating circuits include a photosensitive switch which is energized by light sources located at ground potential.

United States Patent [721 inventors Waiter Pucher;

Sven Bachler, both of Ludvika, Sweden 1211 Appl. No. 810,989 [22] Filed Mar. 27, 1969 [45] Patented July 13, 1971 [73) Assignee Allmanna Swenska Elektriska Aktiebolaget Vnsteras, Sweden [32] Priority Apr. 1,1968 [33] Sweden [31 4338/68 [54] GAS BLAST CIRCUIT BREAKER FOR HIGH ALTERNATING VOLTAGES 3 Claims, 1 Drawing Fig.

[52] 1.1.8. CL... 200/148 {51] Int.-Cl H0111 33/59 [50] Field of Search ZOO/148.4,

[56] References Cited UNITED STATES PATENTS 2,646,483 7/1953 Baker et a1 200/148 (.4) 2,999,143 9/1961 Baker et a1 200/148 (.4)

Primary Examiner- Robert S. Macon Attorney-Jennings Bailey, Jr.

ABSTRACT: A high voltage gas blast circuit breaker is provided with series-connected pairs of contacts, one used to interrupt the circuit being protected, and the other used to close or make the circuit being protected. The contact used for circuit interruption may be operated synchronously to interrupt at or before a currentzero. The contact used for closing the circuit may be operated when the instantaneous voltage across the contact is zero, thereby to prevent line voltage surges during closing. The operating circuits for the contacts are at the high voltage side of the breaker and contain a generator driven from ground by an insulation shaft. The operating circuits include a photosensitive switch which is energized by light sources located at ground potential.

GAS BLAST CIRCUIT BREAKER FOR HIGH ALTERNATING VOLTAGES RELATED APPLICATIONS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to high voltage gas blast circuit interrupters, and more particularly relates to gas blast interrupters having two series-connected contacts, one of which takes all interrupting duty, and the other of which takes all closing duty. The invention is further related to a novel operating circuit for operating the circuit breaker contacts from ground potential, and for charging an energy storage means from ground potential.

2. Prior Art Gas blast circuit interrupters for use in circuits having voltages of about 1000 kv. are known. Such circuit breakers must be capable of interrupting the circuit in a very short time; all poles ofa multipole unit must open and close simultaneously; and, during opening and closing, voltage surges on the line must be limited.

High-speed interruption has been satisfactorily obtained by separating the contacts just prior to a current zero. Devices of this type, sometimes called "synchronous circuit interrupters" are well-known. Similarly devices are well known for operating all poles of a multipole breaker, although some difficulty has been experienced in bringing the operating signal and operating energy from ground potential to the interrupter which is at line potential.

However, a serious problem exists in preventing voltage surges on the line when the circuit interrupter is closed, particularly where the line voltage is at very high voltages such as I000 kv. In the past, switching resistors have been connected in series with the interrupted during closing. Such switching resistors must have a value of the same order as the wave impedance of the high voltage line, for example, 300 ohms. Such low ohmic resistors become extremely large and expensive at the high voltages in question.

SUMMARY OF THE INVENTION In accordance with the present invention, two series-connected contacts are provided for a high voltage circuit interrupter, one responsible for current interruption (hereinafter a gap), and the other responsible for closing the circuit (hereinafter a voltage disconnecting gap). The voltage disconnecting gap is designed specifically to obtain optimum closing characteristics that will create the least voltage surges during closing, and, in particular, may be closed in synchronism with line voltage zero to further decrease possible closing voltage surges. When interrupting a circuit, the breaking gap is first separated, and thereafter the voltage disconnecting gap is separated (without any interrupting duty). The breaking gap is thereafter automatically reclosed (without any closing duty) and, when the circuit breaker is closed, the voltage disconnecting gap is closed.

The closing gap of the above combination may be of the type shown in above noted copending application Scr. No. 661,993 which consists of a pair of spaced fixed electrodes having rounded facing surfaces which may be partly spherical or may follow a so-called Rogowski profile, either of which produce an electric field configuration to prevent breakdown between the electrodes, even though they are closely spaced. An elongated movable contact shaft which is retractable into one of the electrodes is then used to make contact between the electrodes under the driving force of an electrodynamic drive structure. Since the electrodes are closely spaced, the contact shaft need move only a short distance under the high accelerating force of the electrodynamic drive. Accordingly, contact closing can be easily synchronized with a voltage zero on the line to prevent or decrease closing voltage line surges without need for expensive switching resistors.

As a further feature of the invention, the electro dynamic drive circuit and energy source therefor are carried at high voltage and the energy source is charged by means of a local generator driven from an insulation shaft which extends to shaft rotating means at ground potential. Alternatively, the

local generator could be driven by fluid pumped through an insulated shaft from ground potential, or by the compressed gas of the interrupter. While the energy storage means of the drive circuit could be charged directly from the electrical energy at high potential, it is preferred that they be charged from ground so that they operate even though the line is deenergized. Moreover, energy discharge of the drive circuit is initiated by a light source at ground potential which can operate a suitable photosensitive switching means at high potential with the drive circuit. Alternatively, spark gap switching can be used where the spark gap could be gap could be ignited from ground by a laser source which may directly trigger the gap, or may fire a photosensitive switch, which, in turn, triggers the gap.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing shows in partly schematic, cross-sectional DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, there is shown an interrupter having two identical series-connected main breaking gaps l which are, in turn, series-connected by conductor la with two identical series-connected voltage breaking gaps 2. The interrupter is provided with line voltage terminals T, and T, for the phase or pole shown in the drawing. For voltage control, the breaking gaps are bridged by the schematically shown grading capacitors 3. The main breaking gaps 1 may alternatively be provided with schematically shown parrallel-connected relatively high-ohmic grading resistors 4. Each main breaking gap has two stationary nozzles 5 and 6 spaced from one another, which are connected by a sheathlike movable contact 7 surrounding the nozzles 5 and 6. Contact 7 also serves as valve since it cooperates with a sealing member 8 secured to the nozzle 5. Nozzles 5 and 6 are also provided with pressure contact elements 9 and 10.

Each voltage breaking gap 2 has two stationary electrodes I1 and I2 with well-rounded surfaces facing each other, as disclosed in copending application Ser. No. 661,993. Electrodes II and 12 are connected to one another by plug-shaped contact 13 which is axially movable through the electrode 12. When the voltage breaking gap 2 is to be closed, the left-hand end of the contact 13 is moved into a recess 14 of contact 11, which forms a socket-type contact arranged centrally in the electrode 11. The main breaking gaps 1 as well as the voltage breaking gaps 2 are then carried in containers 15 and 16, respectively, which are permanently filled with compressed gas supplied from ground potential G in any desired manner through a hollow support insulator 17.

When the circuit breaker is to be opened, the main breaking gaps I open, interrupt the current and then reclose. The voltage breaking gaps 2 open immediately after the current is interrupted and before the main breaking gaps 1 close and remain open to provide the required insulation for the open circuit condition of the interrupter. The closing of voltage breaking gaps 2 closes the circuit breaker. Opening of the main breaking gaps and closing of the voltage breaking gaps is accomplished by respective electrodynamic operating devices arranged by high voltage potential located close to the associated breaking gaps. Opening of the voltage breaking gaps Each of the electrodynamic operating devices for gaps 1 and 2 consist of induction drive coils l8 and 19, respectively, and capacitors 20 and 21, respectively. Capacitors 20 and 21 are each charged from ground potential by means of motor 22 located at ground, a rotating insulating shaft 23 which extends through insulator 17, AC generators 24 and 25, respectively, transformers 26 and 27, respectively, and rectifiers 28 and 29, respectively. The electrodynamic operating devices are then triggered by light from flash lamps 30, 31 disposed at ground potential, through photothyristors 32 and 33. The light is supplied directly to the photothyristors 32 and 33 through suitable lightcon'ducting members 34 and 35 which extend through the support insulator 17. Obviously, any desired arrangement can be used to apply the light oflamps 30 and 31 to photothyristors 32 and 33, respectively, with suitable means for shielding lamp 30 from thyristor 33 and for shielding lamp 3] from thyristor 32. Note that motor 22 is also used to drive shaft 23a which serves the purpose of shaft 23 for an adjacent pole of the circuit breaker. Similarly, lamps may be connected to the same energy source (not shown) used for lamps 30 and 31 and are in parallel with lamps 30 and 31. During circuit interruption, the circuit breaker operates in the following manner:

When the photothyristor 32 is fired, or turned on by an optical impulse from theflash lamp 30, capacitor 20 discharges through coil 18. Coil 18 is closely coupled to conductive piston 36 which is connected to movable contact 7. A circulating current is induced in conductive piston 36 to drive piston 36 away from stationary coil 18, thereby moving the contact 7 from closed to open position. After seal 8 is opened, there is also a force on contact 7 in the direction of its movement caused by the high air pressure in chamber 15. Air can then fiow through channel 37 in contact 7 into a cylinder space 38 situated behind piston 36. This high-pressure air opens valve 39 so that cylinder space 40 in housing 16 for voltage breaking gaps 2 is exhausted to the external atmosphere though conduit 41 and valve 39. This causes movement of the movable contact 13 of the voltage breaking gap toward the open position. That is, movable contact 13 is connected to two pistons 42 and 43, piston 42 being larger than piston 43. Piston 42 supports a valve seat 44. When contact 13 reaches its open position, seat 44 seals against a seal ring 45. Contact 13 is thus held in its open position due to the pressure on piston 43, regardless of whether or not the channel 41 is under pressure.

During this time the pressure is equalized on both sides of the piston 36 in the main breaking gap and a spring 46 moves the contact 7 back to closed position. The cylinder space 38 is emptied through channel 37 and the-two nozzles and 6. Valve 39 then closes due'to the force of biasing spring 47, and places the channel 41 under pressure again. The opening operation is thus complete.

in order to close the breaker, photothyrlstor 33 is fired by optical impulses from the lamp 31. Preferably, the lamp 31 is ignited by a suitable firing circuit connected to lines 30b and 300 which is responsive to the instantaneous line voltage so that contact 13 can be closed on a voltage, such as zero voltage, which would not cause voltage surges on the line. Capacitor 21 then discharges through coil 19 which is closely coupled to conductive piston 42. A high circulating current is then induced in coil 19 so that movable contact 13 moves away from coil 19 against the force due to the pressure on piston 43. When the seat 44 and seal ring 45 separate, air flows from the channel 41 into the cylinder space 40 and supplies a pneumatic force to move contact 13 to its closed position, and to hold contact 13 closed.

By electric-optic triggering and operation extremely short opening and closing times are achieved so that all the breaking gaps 2 can be simultaneously operated. Furthermore, the short operating times make it possible to synchronize opening and closing of the contacts with line voltage and current. By means of such synchronization and by using main breaking gaps with double nozzles, the breaking power and voltage per breaking gap can be increased and, as a result, the number of breaking elements per pole can be reduced. This is also of great importance from the point of view of simultaneous operation. Furthermore, the requirement of low switching overvoltages can be met without requiring switching-in and protective resistors which, as mentioned above, are extremely bulky and expensive.

The invention is not limited to the embodiment shown. For example, the number of main breaking gaps and the number of voltage breaking gaps need not be the same, but may have any relation to each other. Neither need breaking gaps of the same type be combined in pairs as shown in the drawing. it is also feasible to combine pairs of one main and one voltage breaking gap.

Although this invention has been described with respect to particular embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and, therefore, the scope of this invention is limited not by the specific disclosure herein, but only by the appended claims.

We claim:

1. A high voltage gas blast breaker comprising, in combination:

a. a main breaking gap comprising a first pair of cooperating contacts movable between an engaged and a disengaged position, and being adapted primarily to interrupt an electrical circuit,

b. a voltage disconnecting gap comprising a second pair of cooperating contacts movable between an engaged and a disengaged position and being adapted primarily to close an electrical circuit, and connected in series with said first pair of cooperating contacts,

c. a firstand a second container filled with compressed gas receiving said first and said second pair of cooperating contacts,

d. an operating means connected to said first and second pairs of cooperating contacts and including means adapted to open said circuit breaker in sequence according to which said first pair of contacts disengage, thereby to open a circuit, and then said second pair of contacts disengage, and then said first pair of contacts engage; said operating means closing said circuit breaker by engaging said second pair of cooperating contacts,

e. said second pair of cooperating contacts comprising a pair of spaced fixed electrodes having rounded facing surfaces and a movable elongated contact coaxially disposed with said electrodes and slidable through the center of one of said electrodes into bridging engagement with the center of the other of said electrodes,

t. said operating mechanism including first and second electro-dynamic drive systems for said first and second pairs of cooperating contacts, respectively; each of said first and second pairs of cooperating contacts, respectively; each of said eiectro-dynamic drive systems including an impulse cell, a capacitor and a switching means connected in series; the impulse coil of each oi said systems respectively being coupled to one contact of each of said first and second pairs of cooperating contacts; said first and second electro-dynamic drive systems being positioned adjacent said first and second containers, respectively.

2. The high voltage circuit breaker of claim 1 which further includes means for charging said capacitors; said means comprising a generator means disposed in proximity to said capacitors; circuit means connecting said generator means to said capacitor for the charging thereof, and generator drive means disposed at ground potential and an elongated insulation means connecting said generator and said generator drive means.

3. The high voltage circuit breaker of claim 1 wherein said switching means of said first and second eiectro-dynamic drive systems comprise comprise photoresponsive switching means; and first and second light sources disposed at ground potential for illuminating said phctoresponsive switching means of said first and second systems. 

1. A high voltage gas blast breaker comprising, in combination: a. a main breaking gap comprising a first pair of cooperating contacts movable between an engaged and a disengaged position, and being adapted primarily to interrupt an electrical circuit, b. a voltage disconnecting gap comprising a second pair of cooperating contacts movable between an engaged and a disengaged position and being adapted primarily to close an electrical circuit, and connected in series with said first pair of cooperating contacts, c. a first and a second container filled with compressed gas receiving said first and said second pair of cooperating contacts, d. an operating means connected to said first and second pairs of cooperating contacts and including means adapted to open said circuit breaker in sequence according to which said first pair of contacts disengage, thereby to open a circuit, and then said second pair of contacts disengage, and then said first pair of contacts engage; said operating means closing said circuit breaker by engaging said second pair of cooperating contacts, e. said second pair of cooperating contacts comprising a pair of spaced fixed electrodes having rounded facing surfaces and a movable elongated contact coaxially disposed witH said electrodes and slidable through the center of one of said electrodes into bridging engagement with the center of the other of said electrodes, f. said operating mechanism including first and second electrodynamic drive systems for said first and second pairs of cooperating contacts, respectively; each of said first and second pairs of cooperating contacts, respectively; each of said electro-dynamic drive systems including an impulse coil, a capacitor and a switching means connected in series; the impulse coil of each of said systems respectively being coupled to one contact of each of said first and second pairs of cooperating contacts; said first and second electro-dynamic drive systems being positioned adjacent said first and second containers, respectively. CM,2He high voltage circuit breaker of claim 1 which further includes means for charging said capacitors; said means comprising a generator means disposed in proximity to said capacitors; circuit means connecting said generator means to said capacitor for the charging thereof, and generator drive means disposed at ground potential and an elongated insulation means connecting said generator and said generator drive means.
 2. The high voltage circuit breaker of claim 1 which further includes means for charging said capacitors; said means comprising a generator means disposed in proximity to said capacitors; circuit means connecting said generator means to said capacitor for the charging thereof, and generator drive means disposed at ground potential and an elongated insulation means connecting said generator and said generator drive means.
 3. The high voltage circuit breaker of claim 1 wherein said switching means of said first and second electro-dynamic drive systems comprise comprise photoresponsive switching means; and first and second light sources disposed at ground potential for illuminating said photoresponsive switching means of said first and second systems. 